1. Field of the Invention
The present invention relates to novel hydrocarbon conversion catalysts, and uses thereof in hydrocarbon conversion processes. More particularly, the present invention relates to a catalytic cracking catalyst suitable for the conversion of high metals content hydrocarbon feeds.
2. Description of the Prior Art
Conventional hydrocarbon conversion catalysts are known to become rapidly deactivated by contact with hydrocarbon feeds containing large amounts of metallic contaminants. Typical feeds utilized, for example, in catalytic cracking have been gas oils, even though conversion of heavy petroleum crude oils and residual oils would increase the yield of gasoline obtainable from a barrel of oil. The heavy crude oils and residual oils, such as bottoms from atmospheric or vacuum distillation of crude oil contain large amounts of material having atmospheric pressure boiling points above 1050.degree. F.+ and contain relatively large amounts of metallic contaminants generally present as organometallic compounds, large amounts of nondistillable asphaltenes, i.e. pentane or heptane-insoluble material, large amounts of sulfur and nitrogen and a high Conradson carbon residue. The actual amounts of these materials will vary according to the source of the crude and cut point made during the crude distillation. Tar sand oils, shale oils and liquefied retorted coal present similar processing difficulties. To facilitate the total refining of these heavy hydrocarbon oils, they may be subjected to a hydrogen refining process. Although the hydrogen refining step facilitates handling and further processing operations since it may remove some of the metals, sulfur, nitrogen and polar compounds, it does not significantly affect the asphaltenes and the Conradson carbon residue contents. Consequently, the hydrogen refined heavy crudes and residua still contain large amounts of materials which are normally deleterious to conventional cracking catalysts. The deposition of metals on the catalyst, principally nickel, vanadium and iron is particularly disadvantageous since these metals adsorb on or near active catalytic sites and act as catalytic agents to produce hydrogen, methane and coke instead of the desired more valuable products such as gasoline and light olefins.
It has now been found that the deleterious effect of feed metal deposition on the hydrocarbon conversion catalyst can be minimized with a catalyst comprising a catalytically inert adsorbent, a zeolite, and an inorganic gel matrix comprising a major amount of silica and minor amounts of zirconia and alumina.
Hydrocarbon conversion catalysts comprising a zeolite dispersed in a siliceous matrix are known, see, for example, U.S. Pat. No. 3,140,249 and U.S. Pat. No. 3,352,796. Cracking catalysts containing a zeolite, silica-alumina and clay are also known, see, for example, U.S. Pat. No. 3,449,265. Hydrocarbon conversion catalysts comprising a physical mixture of silica-alumina and a crystalline aluminosilicate zeolite in a siliceous matrix are also known, see, for example, U.S. Pat. No. 3,558,476. Processes for preparing hydrocarbon conversion catalysts containing a zeolite, clay, and silica or silica alumina are disclosed in U.S. Pat. Nos. 3,867,308 and 3,867,310. Catalysts comprising zirconia are also known, see for example, U.S. Pat. No. 3,558,476, U.S. Pat. No. 3,944,482 and U.S. Pat. No. 3,556,988.